The Gilles de la Tourette syndrome-quality of life scale (GTS-QOL): development and validation.
BACKGROUND
Gilles de la Tourette syndrome (GTS) is a chronic neuropsychiatric disorder which has a significant detrimental impact on the health-related quality of life (HR-QOL) of patients. However, no patient-reported HR-QOL measures have been developed for this population.


OBJECTIVE
The development and validation of a new scale for the quantitative assessment of HR-QOL in patients with GTS.


METHODS
In stage 1 (item generation), a pool of 40 potential scale items was generated based on interviews with 133 GTS outpatients, literature review, and consultation with experts. In stage 2 (scale development), these items were administered to a sample of 192 GTS outpatients. Standard statistical methods were used to develop a rating scale satisfying criteria for acceptability, reliability, and validity. In stage 3 (scale evaluation), the psychometric properties of the resulting scale were tested in a second sample of 136 subjects recruited through the UK-Tourette Syndrome Association.


RESULTS
Response data analysis and item reduction methods led to a final 27-item GTS-specific HR-QOL scale (GTS-QOL) with four subscales (psychological, physical, obsessional, and cognitive). The GTS-QOL demonstrated satisfactory scaling assumptions and acceptability; both internal consistency reliability and test-retest reliability were high (Cronbach alpha > or =0.8 and intraclass correlation coefficient > or =0.8); validity was supported by interscale correlations (range 0.5-0.7), confirmatory factor analysis, and correlation patterns with other rating scales and clinical variables.


CONCLUSIONS
The Gilles de la Tourette syndrome (GTS)-specific health-related quality of life (HR-QOL) scale (GTS-QOL) is proposed as a new disease-specific patient-reported scale for the measurement of HR-QOL in patients with GTS, taking into account the complexity of the clinical picture of GTS.
Cavanna
A E
AE
Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, Queen Square, London WC1N3BG, UK A.Cavanna@ion.ucl.ac.uk
Schrag
A
A
Morley
D
D
Orth
M
M
Robertson
M M
MM
Joyce
E
E
Critchley
H D
HD
Selai
C
C
D000328:Adult; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D025341:Principal Component Analysis; D011594:Psychometrics / Q000379:methods*; D011788:Quality of Life; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires / Q000592:standards*; D005879:Tourette Syndrome / Q000503:physiopathology / Q000523:psychology*